This post is about digital low and high pass FIR filter design in VHDL.
Implementing high/low pass filter in the digital domain has a lot of benefits compared to implementations in the analog domain.
The VHDL code for an implementation using convolution is provided. To design the filter, a MATLAB/OCTAVE script was written, in order to derive the filter kernel. The kernel can directly be copied into the VHDL code and can be tested with an VHDL test bench.

This breakout board helps me to interface my FPGA with the DAC900E from Texas Instruments.
The DAC has 165 MSPS and 10 bits which is quite some speed.
The combination FPGA and DAC opens up for experiments with digital signal processing, like making a direct digital synthesizer (DDS), digital modulation and many more. The DAC is fast enough to use it in the TX part for a shortwave radio without any analog mixer required.

This project is a description of how to build a signal generator with an output frequency from 1kHz to 68 MHz.
The frequency generation is handled by a small Programmable Oscillator from Linear Technology the LTC6903.

The control of the Programmable Oscillator is done by the ATMEGA328 microprocessor, the output frequency is shown on a 7 segment display.

The PCB contains a EP3C5E144C8N Cyclone III FPGA from ALTERA, two 8 bit ADCs AD9057 from Analog Devices @ 80 MHz, a FTDI USB2.0 controller and many other things.

The PCB was designed in order to evaluate if such a design is feasible with home fabrication. And it is.
The two ADCs open up many possibilities for signal processing, even though the FPGA is probably not the most powerful.

This is a PCB design using the USB 2.0 IC from FTDI, FT232H – Hi-Speed Single Channel USB UART/FIFO IC, to connect it to the GPIO port of the Altera DE0 development board. The design should also work with other development boards which have a 40 pin connector like the DE2 and others.

This board is to test the implementation of the USB 2.0 controller directly on the PCB for future projects, instead of adding the UM232H evaluation/development board on top of a IC socket as done in earlier projects.